1. Field of the Invention
The system of the present invention relates to the monitoring and control of hydrogen sulfide gas in a waste water stream. More particularly, the present invention relates to a system for continuously monitoring the hydrogen sulfide concentration present in a waste water stream and controlling the quantity and time of automatically injecting a specified chemical into the waste water stream.
2. General Background
In the environmental waste water industry, it is critical that hydrogen sulfide gas, which is a toxic gas in certain concentrations, be monitored and controlled. For example, in a waste water stream such as a sewerage system of a municipality, depending upon the concentration of hydrogen sulfide in the waste water stream, some of it may evaporate into the air in its toxic gaseous form. It is therefore critical that the amount of gas in the atmosphere above the stream be closely monitored and controlled so that people do not come into contact with the deadly gas when working within the confines of the system.
In the present state of the art there are systems for monitoring the quantity of hydrogen sulfide gas in the air above a sewerage stream. However, these present state of the art methods require manual monitoring of the stream during specific time intervals and manual testing of the air through a standard testing procedure. This falls very far short of a system that continuously monitors the air above the waste water stream and controls the level of hydrogen sulfide through chemical injection.
There are several patents in the art which either address the system of monitoring hydrogen sulfide gas, or the chemical compounds which are added to the waste water stream in order to control the amount of hydrogen sulfide gas, the most pertinent patents being as follows:
______________________________________ PATENT ISSUE NO. TITLE DATE ______________________________________ 4,978,512 COMPOSITION AND METHOD FOR 12/18/90 SWEETENING HYDROCARBONS 4,891,205 STABILIZED CHELATING AGENTS 01/02/90 FOR REMOVING HYDROGEN SULFIDE 4,778,609 HYDROGEN SULFIDE SUPPRES- 10/18/88 SION WITH AMINE DERIVATIVE 4,748,011 METHOD AND APPARATUS FOR 05/31/88 SWEETENING NATURAL GAS 4,680,127 METHOD OF SCAVENGING 07/14/87 HYDROGEN SULFIDE 4,515,759 PROCESS OF REMOVING HYDRO- 05/07/85 GEN SULFIDE FROM GAS MIX- TURES 4,443,423 METHOD OF REMOVING HYDRO- 04/17/84 GEN SULFIDE FROM GASES UTILIZING A POLYVALENT METAL CHELATE . . . 4,436,713 METHOD OF REMOVING HYDRO- 03/13/84 GEN SULFIDE FROM GASES UTILIZING A POLYVALENT METAL . . . 4,405,581 PROCESS FOR THE SELECTIVE 09/20/83 REMOVAL OF HYDROGEN SUL- FIDE FROM GASEOUS MIXTURES WITH SEVERELY STERICALLY HINDERED SECONDARY AMINO COMPOUNDS 4,380,586 METHOD AND APPARATUS FOR 04/19/83 PHOTOMETRICALLY MONITORING LOW LEVEL CONCENTRATION OF HYDROGEN SULFIDE IN ALKA- NOL AMINE 4,112,049 ABSORPTION OF SULFUR COM- 09/5/78 POUNDS FROM GAS STREAMS 4,107,270 PROCESS FOR SIMULTANEOUS 08/15/78 REMOVAL OF HYDROGEN SUL- FIDE AND WATER FROM A GAS MIXTURE WITHOUT . . . 2,860,030 RECOVERY OF HYDROGEN SUL- 11/11/58 FIDE AND/OR CARBON DIOXIDE SUBSTANTIALLY FREE FROM HYDROCARBONS AND . . . 2,761,818 RECOVERY OF ETHANOLAMINES 09/04/56 ______________________________________